FortiOS 5.2 supports Netflow v9.0. NetFlow services provide network administrators with access to IP flow information from their data networks. Network elements (routers and switches) gather flow data and export it to collectors. The collected data provides fine-grained metering for highly flexible and detailed resource usage accounting.

A flow is defined as a unidirectional sequence of packets with some common properties that pass through a network device. These collected flows are exported to an external device, the NetFlow collector. Network flow records include details such as IP addresses, packet and byte counts, timestamps, application ports, and input and output interfaces.